Liz thought it would be good to draw our attention to Fuller's Theology, News & Notes publication. The winter 2008 edition was dedicated to the topic of evangelical identity. There are several excellent articles, and most of them interact with an aspect of Bebbington's quadrilateral.
James Bradley, the Geoffrey W. Bromiley Professor of Church History at Fuller, carefully constructs a summary of evangelicalism in the issue. He parses evangelicalism's growth into four stages and examines "a single thread of evangelical theology, the substitutionary atonement, to show how different historical eras and contexts shaped evangelical emphases, and at the same time, how certain elements of the gospel became prominent in the evangelical tradition" (p. 4)